Expanded Polystyrene Insulation Research Articles

УЧЕТ ВЛАЖНОСТИ В ПОВЫШЕНИИ ТОЧНОСТИ РАСЧЕТА ТЕПЛОВЫХ ПОТЕРЬ ЗДАНИЯ

A discrete-continuous approach was applied to the moisture transfer equation, which made it possible to obtain an analytical solution for the moisture potential. The new method was applied to study the unsteady-state moisture regime of the facade heat-insulating composite system with expanded polystyrene insulation and aerated concrete base. It was found that the mass moisture content of building materials achieved in the walls during the period of operation is lower than the mass moisture content used in construction regulations, which makes it possible to increase the accuracy of calculating the transmission heat losses of the building. Calculations of heat losses of a two-storey building in the climatic conditions of Moscow (Russia) showed a decrease in the heating system load by 5 %, and the reduction in heat losses for specific premises of the building ranged from 3.6 to 7 %.

Passive Building Energy Saving: Building Envelope Retrofitting Measures to Reduce Cooling Requirements for a Residential Building in an Arid Climate

In arid climates, a significant portion of the urban peak energy demand is dedicated to cooling and air-conditioning during the summer. The rapid urbanization rates in developing countries, particularly in the Gulf Cooperation Council (GCC), have intensified the pressure on energy resources to meet the indoor comfort needs of residents. As a result, there has been a substantial increase in energy demand, with a 2.3% rise recorded in 2018. Electricity consumption in residential buildings accounted for over 48.6% of the total electricity consumption. The choice of building fabrics used in a residential building can significantly impact the building’s passive performance and carbon footprint. This study aimed to enhance our understanding of how specific fabric details influence cooling energy usage in arid climates. To achieve this, a validation simulation model was initially created as a base case for a residential housing typology in Al Ain, UAE. This was followed by a parametric energy evaluation of various building envelope features. The evaluation was based on the reduction of yearly cooling load energy. The simulation results indicate that incorporating 50 mm of expanded polystyrene insulation into the outside walls significantly reduced energy consumption for cooling requirements in the arid UAE climate. Furthermore, no substantial difference was observed in the various roofing choices, including cool and green roofs, gravels, and sand roofs. Additionally, we concluded that the total solar energy transmittance (g-value) of windows played a more significant role than thermal transmittance (U-value) in reducing solar heat gain within the spaces. These findings should guide strategic decisions on building envelope upgrading for sustainable societies.

Sensitivity analysis of the impact of environmental product declaration values on whole life carbon assessment: A case study using expanded polystyrene insulation for the retrofit of a building in Turkiye

Until recently, reducing the energy required to service a building (the operational energy) was the main aim of controlling carbon emissions from the built environment. It is now recognised that the energy required to make a building (the embodied energy) also has a crucial role in creating a net zero carbon future. The methodologies for quantifying embodied carbon are less developed than those for operational carbon, and more research is required to refine the embodied carbon metrics used when a building’s whole-life carbon emissions are calculated in a Life Cycle Assessment (LCA). One such metric is the Environmental Product Declaration (EPD), a document which can be used in different countries to quantify a product's environmental performance. EPDs are crucial data for conducting an LCA study of a building. However, despite recent efforts to standardise them, there are still inconsistencies between EPDs produced by different countries or manufacturers, even for materials with similar thermal and physical properties. This study considered some of the reasons for variations in EPDs for one product type, expanded polystyrene insulation (EPS). Factors such as (i) the LCA databases and software generators used for the EPDs, (ii) material mixes and manufacturing methods, (iii) country energy production mixes, and (iv) transportation distance from material source to the factory were considered in the analysis. As a case study, this paper examined the effects of selecting different EPDs for expanded polystyrene insulation on the final LCA results from the retrofit of a mid-rise residential building in Turkiye. Differences in EPDs demonstrated a fourfold difference between the highest and lowest upfront carbon impact results of building retrofit. This size of discrepancy indicates the need to choose the most appropriate EPD for a building/location when performing an LCA. Practical Applications Selecting an EPD when conducting an LCA for a new building or retrofit is generally left to the assessor’s judgment and knowledge, which varies greatly depending on the assessor’s background, especially in the construction sector. This study suggests an informed decision-making method over an example of EPS insulation material when the EPD options were none or limited to building locations like Turkiye.

Assessment of different types of bricks in varying wall configurations in an indoor thermal environment for a semi-arid region

This study evaluates the indoor thermal benefits of seven bricks, and their combination with cavity walls, Vertical Greening Systems (VGS), and Expanded Polystyrene (EPS) insulation in a semi-arid Indian climate using EnergyPlus simulations. For walls with VGS and exterior EPS with higher heat capacity, peak summer Operative temperatures (Top) reduced up to 2.3°C, followed by cavity walls and EPS on middle of the wall (up to 1.3°C) compared to their respective bare walls. Interior EPS raised Top by up to 0.7°C. VGS and EPS minimized heat flux fluctuations due to their lower Decrement Factor. VGS exhibited superior indoor thermal comfort, with more occupants satisfied for longer durations compared to exterior EPS. This study suggests that applying VGS or EPS on the exterior (regardless of brick type) is more effective in enhancing indoor thermal comfort during hot days in semi-arid regions .

Influence of degree days calculation methods on the optimum thermal insulation thickness in life-cycle cost analysis for building envelopes in Mediterranean and Semi-Arid climates

The life-cycle cost analysis (LCCA) is one of the most widely used and validated methods to identify the optimum insulation thickness of the building envelope. This method depends on two parameters—heating and cooling degree days (HDD, and CDD). There are various methods for HDD and CDD calculation, the results of which vary significantly depending on the climatic zone. Therefore, this study aimed to analyse the optimum expanded polystyrene insulation thicknesses of a typical wall in Andalusia, Spain, obtained by the LCCA method to demonstrate variations and uncertainties of the results of the LCCA method based on HDD and CDD calculated by the “hourly”, UKMO, and ASHRAE methods, and with different base temperatures in the conditions of Mediterranean and Semi-Arid climates. On average, the HDD values calculated by using the ASHRAE method were lower, by 12.5%, than those calculated using UKMO and the “hourly” method. The CDD values calculated using the ASHRAE method were lower, by 29%, than those obtained using UKMO and the “hourly” method. Consequently, the optimum insulation thicknesses determined based on CDD and HDD calculated using the ASHRAE method were, on average, 14% underestimated compared with the thicknesses obtained using the UKMO and “hourly” methods. The results obtained showed that with an increase in the continentality of the climate, it becomes crucial to correctly use one or another method for calculating degree days to determine the optimum insulation of the building envelope using the LCCA method, which, in turn, requires the development of validation methods.

Study on the flexural behavior of precast concrete multi-ribbed sandwich slabs under different boundary conditions

The sandwich slab is a relatively new form of the structural component with the advantages of high-speed erection and insulation function for precast diaphragm systems. Field static loading tests were conducted on eight precast concrete multi-ribbed sandwich slabs with different boundary conditions. The precast concrete multi-ribbed sandwich slab consists of two structural wythes separated by the expanded polystyrene insulation and integrated by evenly distributed longitudinal and transverse concrete ribs. The effects of different volume ratios of longitudinal concrete ribs, numbers of support edges, and types of end connections were discussed to evaluate the cracking mode, stiffness, degree of composite action, and deflection of slabs. The test results indicate that the cracking behavior of the precast concrete multi-ribbed sandwich slabs was similar to that of conventional solid concrete slabs. A higher volume ratio of longitudinal ribs could provide a more effective composite action. Slabs supported on three edges exhibited a more extended linear stage than slabs supported on two edges on load–deflection response. Bolted connections improved the overall flexural performance of the slab through the rotational restraint introduced at the ends of the slab, and bolted angle connections displayed a preferable end-restraining action than through-bolt connections. A theoretical method was developed to calculate the slab deflection under the effect of the bolted connections. In addition, a nonlinear finite element (FE) analysis was performed and validated by the experimental results.

Shear Transfer Mechanism between CFRP Grid and EPS Rigid Foam Insulation of Precast Concrete Sandwich Panels

An experimental program was implemented to investigate the shear transfer mechanism of carbon-fiber-reinforced polymer (CFRP) grids and expanded polystyrene (EPS) rigid foam insulation in three wythe precast concrete sandwich wall panels. The purpose of the research was to measure the shear flow capacity and to observe the failure mode(s) of precast concrete sandwich panels manufactured with a CFRP grid shear transfer mechanism between wythes. Six precast concrete sandwich panels were examined by push-out tests in which the center concrete wythe was pushed downward with respect to two outer concrete wythes. It was observed that the average shear flow capacity of the specimens having 2 in (51 mm) thick foam was higher than that of the specimens having 4 in (102 mm) thick foam. In addition, stiffness decreased significantly when the thickness of the EPS insulation increased. The failure mode for the panels included relative displacement between the center concrete wythe and the outer concrete wythes. Test results showed that panels tended to fail by CFRP grid rupture, CFRP grid pull-out, and loss of bond at the concrete/foam interface. Further tests should be performed to fully comprehend the nature of the shear transfer mechanism between the specific CFRP grid used and EPS rigid foam insulation.

Thermal-mechanical properties of polystyrene insulation board under defect condition and their influence on lining structure of conveyance channel

The seasonal frozen soil area in the north of China has a low temperature in winter, and laying an insulation board is an effective method for mitigating the frost-heaving damage to the lining structure of the conveyance channel. However, the insulation board has a certain defect rate during installation and later operation, which changes its thermodynamic and mechanical properties, thus affecting the safety of the lining structure. In this study, an expanded polystyrene insulation board was adopted and its thermal-mechanical properties were examined under the condition of defects. Then, the effect of the insulation board with defects on the lining structure was analyzed by conducting numerical simulations, taking a conveyance channel of a Jiaodong water diversion project as an example. The experimental results showed that with the increase in freeze–thaw times and decrease in defect size, the moisture content and thermal conductivity of the insulation board with defects increased. After 28 freeze–thaw cycles, compared with the complete insulation board, the moisture content and thermal conductivity of the insulation board with 20-mm defect decreased by 21.63% and 4.33%, respectively. With the increase in freeze–thaw times and defect size, the elastic modulus and compressive strength of the insulation board with defects decreased. After 45 freeze–thaw cycles, compared with the complete insulation board, the elastic modulus and compressive strength of the insulation board with 20-mm defect decreased by 17.76% and 6.67%, respectively. The numerical simulation results showed that when air media existed in the defects, the deformation and stress change of lining were not distinctive. When ice media were present in the defects, the larger the defect size, the larger the freezing depth of the channel, the larger the normal frost-heaving displacement of the lining surface, the greater the possibility of tensile damage of the lining inside, and the more significant the outward expansion trend of the canal slope lining. In the middle of a shady slope, compared with the complete insulation board, the average freezing depth of the insulation board with 20-mm ice defect increased by 2.29 times, the maximum normal frost-heaving displacement increased by 4.50 times, and the normal frost-heaving stress and tangential freezing stress increased by 16.86 and 7.47 times, respectively. These results can provide a theoretical reference for the safe and efficient operation of water diversion projects in dry and cold regions.

Exploring the applicability of expanded polystyrene (EPS) based concrete panels as roof slab insulation in the tropics

Heat transfer through roof slabs significantly increases the operational energy consumption of buildings. Therefore, passive implementations are necessary to improve the thermal performance of roof slabs in tropical climates. This paper presents a novel roof slab insulation using expanded polystyrene (EPS) based lightweight concrete panels. The workflow consists of field experiments and numerical simulations performed in Design Builder. Moreover, we offered a holistic life-cycle approach to investigate the economic and environmental feasibility of alternate forms. Accordingly, the roof slab with 75 mm EPS insulation and a white exposed surface performed satisfactorily. Corresponding decrease in life cycle cost, carbon emission (kgCO2e), and operational energy consumption were 8.3%, 20%, and 41%, respectively. The overall eco-efficiency index (EEI) implies that the recommended insulation system is environmentally and economically feasible under tropical climatic conditions. Further, manufacturing EPS concrete is eco-friendly since it reduces EPS waste content which does not decay through natural means.

Experimental study on dynamic effect of external insulation on indoor thermal environment and energy consumption

In this paper, two identical model buildings were built, one of which adopted 38 mm Expanded Polystyrene (EPS) board as the external insulation. Under the same heating set-point temperature, the dynamic change process of indoor thermal environment and heating energy consumption of EPS insulation building and non-insulation Reference building was compared and monitored. Results show that under the same heating set-point temperature, the indoor temperature of the two buildings can quickly approach the set value in about 20 min. However, the temperature rise of the internal surface of the wall lags behind. After several hours, the advantage of the temperature rise of the internal surface of the EPS building gradually appeared. The energy consumption of the two buildings is similar in the initial heating period of 20 min, and the energy saving rate of EPS building increases slowly with the increase of the heating duration. The energy saving rate is about 1%–26% in the range of 0.5–8 h intermittent heating in hot summer and cold winter zone. The change curve of cumulative temperature rise ratio with heating time is proposed to evaluate the dynamic improvement effect of external insulation on indoor thermal environment. This research provides a reference basis for the development of energy conservation.

EXPERIMENTAL STUDY OF ENERGY EFFICIENT THREE-LAYER REINFORCED CONCRETE WALL PANELS WITH FLEXIBLE LAYER CONNECTIONS

The connections between the panels are the most critical structural elements that determine the performance of the building. The article highlights the results of testing the strength of flexible ties of three-layer reinforced concrete exterior wall panels with expanded polystyrene insulation by the static method. Studies were carried out on the mutual shift of the outer layer of the panel in relation to the inner one when testing concrete layers in accordance with the control values. The results of the experimental studies have shown that the use of metal flexible connections to connect the outer and inner layers of three-layer wall panels with insulation provides strength and reliability of structures under static loads. The tested three-layer reinforced concrete exterior wall panels, designed for large-panel housing construction of the 105 series, fully comply with safety requirements during operation.

Thermal Performance Assessment of External Wall Construction for Energy-Efficient Buildings

Building envelope such as external walls are still constructed from poor materials which results in higher heating and cooling loads thereby raising energy bills. Improving building energy efficiency with advanced technologies is being sought. In this context, a numerical study was conducted to solve the coupled heat transfers through a standard wall structure used in Libyan residential buildings. Different techniques were compared to reduce the thermal transmittance of the traditional wall structure for saving energy including the application of radiant shield, low-e coating, insulating filling and external insulation. The numerical results revealed that the thermal radiation inside the cavities of hollow block is important and accounts for 21% of total heat transfer, while conductive and convective heat transfer contributes by 65% and 14% from the total, respectively. The obtained thermal transmittance value of the common wall structure was considered as high as 2.33 W/m2·K due to lower resistance of wall elements. The adoption of 50 mm layer of expanded polystyrene insulation (EPS) to the exterior wall showed the best thermal performance with a reduction of thermal transmittance by 45%. On the other hand, filling the interior of cavities with EPS resulted in a 37% reduction of thermal transmittance compared to 20% of using 3 mm aluminum foil as a radiant barrier in the middle of the cavities. The last case was less effective with a reduction of almost 10% when a commercial coating of 0.4 surface emissivity was applied to the interior of cavities.

Effect of HVAC system size on the optimum insulation thickness of the buildings in different climate zones

Thermal insulation is one of the most effective methods of reducing energy consumption in buildings. Therefore, the parameters influencing the optimum insulation thickness are widely investigated. In this study, the optimum insulation thickness is obtained using the life cycle analysis method and the genetic algorithm by considering the size of the heating and cooling systems as an optimization variable, which has not been addressed in the earlier researches. Furthermore, the effect of the climate conditions on the optimum insulation thickness is comprehensively studied using five different climate zones, including Hot-Dry, Cold-Dry, Moderate-Humid, Hot-semi Humid, and Hot-Humid. It is found that the optimum thickness of expanded polystyrene insulation increases between 5%-19% considering the size variation of the heating systems including the central heating system and wall-hung gas boilers. By size variation of the cooling systems including the evaporative cooler and split air conditioner, this increase is between 8-19%. This is because the cost reduction due to the reduction of the required size of the heating and cooling systems can be expended for insulating the building with larger thickness which results in lower energy consumption. Based on the obtained results, the energy cost saving increases between 3.5%-14.5% and also, the payback period decreases about 1 to 3 months, depending on the considered heating and cooling systems and climate zone. The results confirm that the optimum insulation thickness can be determined with significant inaccuracy, ignoring the size variation of the heating and cooling systems as a result of thermal insulation.

Compressive loading of structural insulated panels and conventional stud walls: a study

Structural insulated panels (SIPs) are structural elements comprising a core of expanded polystyrene insulation sandwiched between two oriented strand boards. They can replace conventional joist floors and stud walls in low-rise residential construction. Three identical samples of full-scale SIP walls and stud walls were tested according to ASTM standards and experimental results for the specimens were obtained in terms of their ultimate load capacity and failure mechanism. Comparison of the load–deformation diagrams of the SIPs and stud walls showed that tangential stiffness variation of the former occurred in the hardening mode, whereas the variation for the latter was in two stages, hardening and softening. Regarding compressive loading, the results showed that SIPs are as good as conventional wood framing of the same size. Therefore, SIP walls are very efficient in the case of axial compressive loading.

Environmental life cycle assessment study of an external wall

In the current economic scenario, sustainable development goals are pursued with the aim of creating a sustainable industrial scenario. Industrial sectors responsible for high levels of emissions and consumption, such as the construction industry, need to be thoroughly analysed, focusing on the use of recyclable and eco-sustainable materials. In this regard, this work proposes an environmental life cycle assessment study, which aims to quantify the environmental impacts of a standard designed external wall and evaluate the use of recycled materials in its insulation layer. An external wall with expanded polystyrene insulation has been chosen. Six environmental impact categories have been considered: 'acidification'; 'eutrophication'; 'global warming potential'; 'abiotic depletion – elements'; 'abiotic depletion – fossil fuels'; 'ozone layer depletion'. Results show that the reinforced concrete layer has the most significant contribution to all the analysed impact categories. Moreover, comparing the insulation layer with different percentages of recycled expanded polystyrene, it has been found that the impact categories majorly influenced are the 'global warming potential' and the 'abiotic depletion – fossil fuel'.

A numerical study on the through thickness shear behavior of EPS sandwich panels

The expansion of industry has rapidly increased the need of energy; necessitating a greater usage of energy resources and posing substantial environmental dangers in the process. Thus, an energy-efficient modular building system appears to be a must-have choice for the India's required mass housing at affordable cost, while the environmental concerns are also looked into account. Insulating Construction Panels are one of the pre-casted building materials; comprising of a core panel of expanded polystyrene insulation encased in galvanized welded steel reinforcing mesh and shear connectors, which is then placed to the site with pressurized concrete skins on both the sides of the core. The structural integrity of these buildings, on the other hand, is heavily reliant on the functioning of these shear connectors and the degree of composite action (DCA). The present study aims to develop a full scale computational model of a single storey building made up of modular EPS panels, to study the effect of spacing and the consequences of different kinds of shear connector failures. Furthermore, the effect of door and window openings on the structural responses of the EPS panel building are discussed. The through thickness shear behavior of these materials are also investigated using multiple static and dynamic analyses steps. The mechanical behaviors of these panels are observed to be widely varying with the spacing, diameter, and adequacy of the shear connectors. The results infer that the present work seems to be necessary for the safety assurance of the insulated precast building panel structural systems, which has a lot of potential for practical usage and thus can help to accomplish the objectives of efficient and economical sustainable building systems in the upcoming years.

Impact of dynamic thermal conductivity change of EPS insulation on temperature variation through a wall assembly

This paper evaluates the effect of dynamic thermal conductivity (λ) change of expanded polystyrene insulation (EPS) on temperature change through a conventional wall assembly at varying positions of the insulation within the assembly in question. According to the findings, in the case of the application of the variable λ-value of the insulation, compared to that obtained when the constant λ-value for polystyrene (EPS) insulation is adopted in the same conditions, the temperature profile through the wall assembly during the daytime is greater. In the event of applying the constant and variable λ-values, the temperature shift on the inside is seen to decline as the location of the insulation material is positioned towards the surface of the inner wall. The highest level of time lag between position 1 to 2 is over 1.3 h and around 3.47 h between position 1 and 3, and as the density level of the insulation materials rises, it leads to better transient thermal performance due to a lower temperature rise on the inside wall surface. These results suggest that considering betterment in the insulation's thermal conductivity would provide the most performant wall configuration by placing the material in the middle of the wall assembly, taking into account the change in the thermal conductivity of the insulation.

Optimizing thermal insulation of external building walls in different climate zones in Libya

An efficient way to reduce the energy required for conditioning buildings and therefore to reduce CO2 emission is the use of proper thermal insulation in buildings’ external walls. This measure requires data from metrological stations that can be used in the optimization of the thermal insulation. The main objectives of this study are to construct thermal climatic zones for Libya and to specify the optimum insulation thickness for external walls for the different zones. This work is comprehensive as the metrological data from all existing 33 weather stations has been collected and used for identifying thermal zones. For the optimization of the construction of external walls, the most commonly used local wall structures are investigated: hollow concrete block, limestone block and hollow brick. In addition, four thermal insulation materials: extruded polystyrene, expanded polystyrene, rock wool and foamed polyurethane are used with every wall type. Optimum insulation thickness, energy savings, energy cost and payback periods were estimated for the 33 locations using life cycle cost analysis. A map is constructed for the thermal zones based on degree-day values for the entire country. The results show that limestone blocks with expanded polystyrene insulation form the optimum wall construction as it provides the minimum total cost for all locations. Depending on the Degree-day values, the optimum insulation thickness varies between 5.4 and 15.3 cm across the country with energy saving varies between 28 and 178 $/m2. Using the optimum thickness, the average CO2 emissions can potentially be reduced by about 85%. Finally, a contour map represents the optimum thickness of expanded polystyrene is presented in this work.

Humidity-Dependent Thermal Boundary Conductance Controls Heat Transport of Super-Insulating Nanofibrillar Foams

Summary Cellulose nanomaterial (CNM)-based foams and aerogels with thermal conductivities substantially below the value for air attract significant interest as super-insulating materials in energy-efficient green buildings. However, the moisture dependence of the thermal conductivity of hygroscopic CNM-based materials is poorly understood, and the importance of phonon scattering in nanofibrillar foams remains unexplored. Here, we show that the thermal conductivity perpendicular to the aligned nanofibrils in super-insulating ice-templated nanocellulose foams is lower for thinner fibrils and depends strongly on relative humidity (RH), with the lowest thermal conductivity (14 mW m−1 K−1) attained at 35% RH. Molecular simulations show that the thermal boundary conductance is reduced by the moisture-uptake-controlled increase of the fibril-fibril separation distance and increased by the replacement of air with water in the foam walls. Controlling the heat transport of hygroscopic super-insulating nanofibrillar foams by moisture uptake and release is of potential interest in packaging and building applications.

The position of the maximum wetting plane in building enclosing structures

We investigate the maximum wetting plane position in two enclosing structures: the first enclosing structure is with aerated concrete base and mineral wool insulation, the second enclosing structure is with aerated concrete base and expanded polystyrene insulation. Two fundamentally different cases of the maximum wetting plane are obtained. For the enclosing structure with mineral wool insulation, the maximum wetting plane is located between the insulation and the external stucco. It was found that when the indoor climate parameters or thicknesses of layers change, the position of the maximum wetting plane does not change. For the enclosing structure with expanded polystyrene insulation, the maximum wetting plane is located inside the insulation layer. It was found that when the indoor climate parameters or thicknesses of layers change, the position of the maximum wetting plane also changes. In terms of application result for calculation, an enclosing structure with aerated concrete base and expanded polystyrene insulation is significantly more sensitive to climate parameters than an enclosing structure with mineral wool insulation. It becomes possible not to obtain the maximum wetting plane position in encloses with mineral wool, and to use described calculated position, therefore, it can save time of engineers during the moisture regime calculation.